The 49ers did not take the Jaguars lightly. And it showed on Sunday at Wembley Stadium.

“We have the most paranoid staff in the National Football League,” 49ers safety Donte Whitner said. “We go over things so many times that when you go in the game, you could do it in your sleep.

“They made sure we weren’t sleep-walking.”

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Said left tackle Joe Staley, “It think it’s great to be paranoid and great to play never-comfortable. To always think about every worst-case scenario beforehand so you don’t have to react when that happens.”

The 49ers proved on the second play of the game just how seriously they were taking the Jaguars, who have been outscored 264-86 while losing their first eight games of the season.

The 49ers unveiled their version of the “lonesome end.”

The 49ers call it, fittingly, Big Sleeper.

The 49ers made multiple substitutions after the first play of the game. Fullback Bruce Miller acted as if he were running off the field, but he stopped just short of the sideline. The Jaguars did not send any defender to cover him.

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Quarterback Colin Kaepernick lofted the pass to Miller, who caught the ball and ran 43 yards down the right sideline before Jacksonville free safety Josh Evans pushed him out of bounds.

“We’ve practiced it a lot,” Harbaugh said. “We called it before. We called it in the Jets game last year, and the Jets called a timeout before we had a chance to get the ball snapped.”

On that play, Kaepernick had been on the field to run a play out of the read option. He then appeared to exit as Alex Smith returned under center.

This time, the Jaguars coaching staff and the players on the field were asleep at the wheel and did not get a timeout called. The 49ers went on to score a touchdown on Frank Gore’s 19-yard run to cap an eight-play, 76-yard drive.

The 49ers got off to a strong start Sunday with touchdowns on their first four offensive possessions. They went for the knockout blow early, and the Jaguars did not have the firepower to make any kind of serious threat.

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All week the 49ers spoke about the dangers that awaited them. Perhaps, the 49ers made it look so easy against the Jaguars because they convinced themselves they expected to face a difficult opponent.

“That wasn’t just lip service,” Harbaugh said. “We watched Jacksonville and it was on the tape. They’re very talented football players and they’re very well-coached. They’ve played in a lot of tight games – haven’t won a game yet, but you get the respect off the tape.”

But, ultimately, the 49ers approached this game thinking about only one team: The 49ers.

“We wanted to get better as a team,” Harbaugh said. “We wanted to improve, and I felt like we did that.”

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The 49ers (6-2) moved a half-game behind the Seattle Seahawks in the NFC West standings. The Seahawks (6-1) face the St. Louis Rams on Monday night.

The 49ers, who spent Sunday night in London and were scheduled to travel back to the Bay Area on Monday, have “opportunity” practices scheduled for Tuesday and Wednesday, Harbaugh said. The workouts are designed for some of the players who do not see much playing time.

The team has mandatory days off Thursday through Sunday as part of their bye week.